Hope you will take it positively.
Apparently you have erred.
1. Probably you did not seek any approval to attend classes on Saturday and Sunday and complete the course and no approval was granted too by the competent personnel. Is your manager competent person to grant approval? He might have backtracked after discussing with his authority. You alone would know you wanted to seek proper approval or just wanted to take your boss in confidence and complete the course without obtaining proper approval in writing.
2. The HR conveyed its decision ‘ Either work or study’ .
3. Does the company have its education policy and encourage employees to do some courses?
4. Is it stated in appointment letter issued to you that you can not undertake any activity ………………..course without advance application and explicit approval ? Usually it is stated so!
5. Did you state reason of resignation in notice of resignation?
6. Did you minute that you have not been allowed to serve the notice period? How would you prove that you were prohibited from entering/attend office……………………………..i.e. by audi/visual/written record? If you can prove then you are eligible for wages during this period. If company had asked you to remain out of office during notice period in writing then it would have affirmed that you would be paid wages. If this communication has been issued to you then produce it on record……………………..or make the person that stated so agree to it!
7. Acceptance of resignation might have noted in your personnel file and that it was sent by post, ……………………….informed in office!!! Did you ever minute it in writing on record under acknowledgment?
8. How does FnF statement dated 12.02.2013 show last date as 20.02.2013?
9. If resignation was not accepted you could have easily responded that your resignation has not been accepted, then how come FnF statement has been issued and sent to you? You could have withdrawn the resignation before acceptance.
10. If it is wrong then if you have pointed out errors it is OK.
11. Leave encashment as per enactments applicable to the establishment and wages for days worked has to be computed in FnF statement.
12. You were not forced to resign hence it is not forced resignation.
13. You had no option but to resign that is what has been cultivated by your lawyer.
14. If you disagree discuss with your lawyer.
15. You could have approached lawyer before submitting resignation and could have proceeded under expert guidance of your lawyer and he could built enough favorable record.
16. The company may reconcile during reconciliation or you shall have to contest the matter.